The term "stability" should not be used outside of the major Linux distributions such as Debian and Fedora. For a distribution to be stable over the long term it needs a large enough community, a stable governance model, and a reasonable build system where one maintainer cannot take unilateral action without it being discovered.

A cute name and a university student somewhere does not constitute stability, no matter how good the intentions. It's not a bad thing, but you have to know what you get yourself into. Most of the distributions listed in the article belong to the latter category.

Immutable systems are great for embedded, network equipment, appliances and industrial applications, and specialized distributions for those applications have largely been immutable for a long time already. Nobody really wants an immutable system for their main desktop, because working is all about mutating state. You write may write documents, save bookmarks, install plugins, or try new software. Those are the things really immutable systems like kiosks wants to disallow.

So in order to make for usable software these desktops generally split your system into a mutable user part and an immutable system part. That's basically how unix-like desktops have worked since forever. Stuff in /bin and /sbin is only changed by the package manager. So the fit is quite good, but it also means it really isn't as useful as it's made out to be. That's why most people don't use them.

The use case is mostly for rolling back updates, not really running from readonly filesystems or preventing change in other ways, but most distributions already do that. You can roll back updates with both dnf and apt. It's not perfect and doesn't always work, but mainly from a lack of testing. With snapshots it's pretty much infallible though.

My recommendation if you really want something that "just works" is to install one of the major and time tested distributions. Pick Debian if you don't know what to choose. And then learn how to use it. Anything these tiny experimental distributions offer, such as running off read only filesystems or rebuilding it for your brand of cpu, or testing a new desktop environment, is likely possible in Debian too. With the added benefit of it being around in 20 years. And the core distribution is less likely to break in some way because some maintainer found inspiration for something. As long as you don't run untrusted stuff as root, stay out of the system files, and generally let the package manager do its job, you're going to be fine.

What I would like to see a desktop distribution work on is basically the same things as 20 years ago which still isn't really done outside some exploratory work (probably because it's actually hard):

- Packages on a user level where it is easy to install new stuff without touching the system area. More tricky in practice than in theory because of state changes to configuration files, saved file formats etc. But some should be easier than others.

- Desktop software service accounts, just like we do for server software. Mostly relevant for larger packages such as Firefox, Libre Office, movie players.

- Integration with popular third party package managers from the language ecosystems. Most language packages are anemic. All the powers that a package manager gives, reporting, listing untracked files, listing changes, rolling back updates, should be available for them by integrating directly with them. Package definitions should be able to be imported without manual work.

- Package managers should have at least some knowledge of an application's access patterns to help with application confinement. Still today things like selinux policies are packaged are separate entities and managed with external tools, which brings a lot of complexity since all possible configurations must be supported there. A package manager knows more about the system and could handle these files. Confining desktop software is a usability problem more than a technical one, but it is clear that desktop environments needs something to build on to make it practical.